BISMARCK, N.D. (AP) - The Army has formally ended further environmental study of the Dakota Access oil pipeline's disputed crossing beneath a Missouri River reservoir in North Dakota.

The Army published notice Friday in the Federal Register that it's scrapping the study launched last month by the Army Corps of Engineers. The study was ordered amid concerns from the Standing Rock Sioux and other Native American tribes that a pipeline leak beneath Lake Oahe would pollute drinking water.

President Donald Trump later pushed to advance pipeline construction. The Army gave Texas-based developer Energy Transfer Partners permission for the crossing on Feb. 8.

Pipeline opponents have continued to call for more study. The Indigenous Environmental Network says more than 100,000 comments have already been submitted.

The Standing Rock and Cheyenne River Sioux also are fighting the pipeline in court.